Gene expression in soleus muscle of mouse inbred strains LG/J and SM/J

Variability in muscle mass significantly impacts energy expenditure, influencing preponderance to obesity and recently it has been reported that there is a positive association between muscle mass and longevity in older adults. Muscle fibre cross-sectional area (CSA) and proportion of different fibre types are important determinants of muscle mass, function and overall metabolism. Genetic variation plays a substantial role in phenotypic variation of these traits but the underlying genes remain poorly understood. We identified QTL associated with these muscle fibre phenotypes and hypothesized that if the phenotypic effect of the QTL was brought about by the allele specific abundance of transcripts encoded by genes within the QTL, such genes would be differentially expressed in the transcriptome between the parental strains. In this experiment, the expressed transcriptome in soleus muscle of mouse LG/J and SM/J strains was examined by measurement of gene expression on microarrays to facilitate nomination of candidate genes within identified QTL. Hypothesis driven analysis of differential expression in soleus muscle was performed between LG/J and SM/J strains for the genes in the most robust QTLs affecting fibre CSA or % Type I fibres.